Brush holder for electric motors



May 29, 1928. 1,671,533

J. LINDALL.

BRUSH HOLDER FOR ELECTRIC MOTORS Filed Jan. 21, 1927 2 Sheets-Sheet l May 29, 1928.

1,671,533 J. LINDALL BRUSH HOLDER FOR ELECTRIC MOTORS Filed Jan. 21, 1927 2 Sheets-Sheet 2 Patented May 29, 1928.

1 UNITED STATES JOHN LINDALL, OF BOSTON, MASSACHUSETTS.

BRUSH HOLDER FOR ELECTRIC MOTOR-S.

Application filed January 21, 1927. Serial No. 162,467.

This invention has for its object to provide a simple, compact and efficient brush holder which is capableof substantial movement toward and fromthe commutator of the motor in close or narrow quarters, with the brush in I iiXed= relation to the brush holder.

. The brush holder is especially adapted for use wltli-motors employed to propel railway cars having low floors below which the motor is located in substantially close pron imity thereto.-

To this end, the brush holder is provided with a supporting member having a bottom wall, and abovewhich is located a lever pivoted at its rear end and having its front orv freeend to which the brush is firmly secured, extended beyond said bottom wall.

The brush-carrying lever is constructed so as to normally leave a substantial space between it and said bottom wall, so as toenable the lever to be moved by a spring the desired or required distance toward said bottom wall as will permit the brush rigid ly attached to the lever to be worn the desired or required amountbefore being replaced.

The bruslrcarrying lever has co-operating with it a stop to limit its movement under the influence of the spring referred to, and thereby prevent contact of the lever with the commutator and avoid damage to the latter.

These and other features of this inven tion will be pointed out in the'claims at the end of this specification.

Fig. 1 is a side elevation .ofa portion of a commutator and a brush holder embodying this invention;

Fig. 2, a view. like Fig. 1. with the casing for the brush holder shown in section;

Fig. 3, a, plan of the brush holdershown inFig.2; I .f

Fig. 4. a view like Fig. showing-the brush'holder in the position it occupies when its'brush has been worn out; and Fig. 5. a view like Fig. 2, showing a modified form of brush holder. v

Referring toFigs. 1 to 4 inclusive, 10 represents the commutator of an electric motor such as is now commonly used on electric railway cars forpropelling the same and which is mounted on the truck below the floor of the car.

The commutator 10 has co-operating with it a brush '12, of usual construction and herein represented as a block of carbon,

which may be curved as represented in Figs. 1 to 4, and inserted into a curved socket 13 at the outer end of a lever 1d provided in the present instance with substantially parallel curved arms 15, 16 spaced apart and connected by a bottom member or web '17 attached to a hub 18, which is mounted to turn on a pivot pin 19 extended through the opposite side walls 20, 21 of a supporting member.

The supporting member referred to is provided in the present instance with a bottom wall 22, which extends but partially the length of the side walls 20, 21 and is provided at its front end with an upturned flange or wall 23, which co-operates with the bottom member 17 of the brush-holding lever 1-1 -to limit the movement of the latter toward the commutator 10.

The bottom wall 22 has extended from it a curved rear end wall 25 from which extends top wall 26, which is materially shorter than the bottom wall 22.

The top end and bottom walls 26, 25 and 22 co-operate with the side walls, 20, 21 to form a casing or housing in which the rear portion of the brush-holding lever 14 is ocated, and which casingis open at its top for the passage into the casing and through the-bottom wall EZQ-thereof, of a rod for supporting a coiled or helical spring 81, by means of which the brush 12 is held in firm engagement with the commutator 10.

The rod 30 is extended below the bottom wall 22 into a boss 32 on the casing or housing and is secured thereto by a pin The rod 30 is extended upwardly through 'an opening 34 in the bottom member 17 of the brush-holding lever 14, and has mounted on it a bushing or sleeve 35 provided between its ends with an annular flange 36, which bears upon the upper surface of the bottom-member 17 of the lever 14.

' The coiled spring 31 has its lower end bearing against the flange 36 and its upper end against a washer 37 mounted on the rod 30 below an abutment member shown as a cap or nut 88. -A locking washer 39 for the cap or nut 38 is also preferably provided and mounted on the rod 30.

The side wall 16 of the casing is provided as shown with a laterally extended flange 42 (see Fig. 1) having one or more hubs 43 through which are extended stationary sup-- porting-members or rods The brush-holding lever 14: is electrically not shown, and is provided with screws 52,

connected with the top wall- 26 oi; the casin by a flexible conductor 45, which 's fastened to the bottom member 17 of the lever 14;.

and to the top wall 26. V

The side wall 15 of the'casing or housing is provided with a terminating 5( having a bore 51 for the insertion of a conductor,

lug andhousing'. The socket I3'for the brush 12- is prefer by which said conductor is secured to said i ably provided with" a movable"front 'wall54 by whichthe brush 12' is firmly clamped against thejopposite or rearwall 55 by nieansf of screws 56:, which extend through the brush and areengaged with threaded holes in th'erear wall It may be preferred to use a curved. brush and provide the brush holder with a curved: socket as represented in Figs. 1 'to 4, but

. represented 'in Fig. 5."

In Figs'l and 2 ,'the brushis represented as newand the pressure withwhich it bears against the commutator is controlledty adjusting the 'nut'38ontherod' 30 to com press the spring the"'properor desired amount. Asthebrush is worn, the spring expands and'moves the brush-holding lever 14 towardthe'bottom'wall22 of the casing,

until thebru'sh hasbeen worn to the point where further. moi emen't' of the lever toward the commutatorjshould be prevented. l In the l present instance, this point is reached when the lever 1&"engages the front Wall 23fof thec'asing, whichfwal'l acts as a stop to prevent further movement" of the lever and its brush toward the commutator. At such time, the leverl lfis. in the'position represented'in li i'g f, and is removed from the commutator and prevented from contact ing therewith: l It will be observed that the front end of the'brush-carrying lever injthe normal positidn of the latter, is extended below the bottom wall 252 (see Figs; land 2), and to obtain "thedesired movement of the lever necessary to enable the brush 12 rigidly attached'to the lever, tobe worn the desired or required amount, as represented'in Fig. 4, the brush-carrying leve'r has its intermediate portion suitably shapedto provide asub'stantial space "between its under surface andthejstop orfront wall.23;"

v In the present instance the intermediate portion'of the bru'sh-carryinglever is provided with a relatively deep/curved portion 60 by meansofwhich 'th'e'newibrush 12, shown in Fig. 2,c-an be wornofl to the extent represented in l;'whenthe'lever is engaged/with itsxstop 23. 7

It. will. further-be observed, that; the bottom wall 2201f the housingior supporting member and the brush-holding lever are curved and substantially concentric with the I commutator, which'e'n'ables the brush-holder to: ts ..Q?}. 1: relfltlvely @1088 P imity to the commutator, and thereby enables the brush holderto be used in quarters where the space or headroom is restricted, as in the'case of railway ca-rs'havin'g low V l I r ,I, H It will further be observed that the brush being in fiXedrelationto its: holdii'ig lever co-operates with the commutator topbtai ri inax'imum' electrical efiiciency and avoids:

the so-cal lcd flash-overs, in which an are starting atthe brush Contact extends until it reacljies a grounded" port on oiithemoto'r', with attei'idrng dan'iage to the motor The bottom wall 22- ofthe siipporting' 1 member serves not only as a meansfor chorin'g' the lower end oii'the rod 30' but also as a protection against damage to the connection 45 and the reanportion' of- 'the lever in caseof severe arcing between the commutator and said bottom wall, especially as the voltage of thear'c inbreases' as it pro gresses away from the brush toward 1 the pivot for thebrush-carryinglever;

It will be observed by reference to Figs.

1, 2, 4 and 5 that the brush-carrying.lever is of substantial length-and has its pivot 19 substantially in a 'plane tangential to the commutator at the point of contac'toi' the brush with thecom1nutator,"with'theresult that the point of contact of the nonadjustjable brush asit wearsremai'ns substantially in the same radial plane passing-"through the brush at the'initi'al point of icontactof anew brush, which serves to" maintain the efficiency of the apparatus at. its'maximnm whilethe brush is being worn.

One embodiment of 'tlie invention is. herein shown, but it is notldesired to limit the invention to' the particular construction Shown. pm v r V, What is claimed is: I 1. In a brushholder for electricv motors and the like provided with a commutator,

in combination, a casing open "atitstopand provided with a bottom wall having'aiijupturned front' wall, a "brush-holding, lever having its rear end located withih said casing and pivoted thereto and having itsfi'ont end extended beyond the"upturnedi front wall of said casing, a brush securedcto t'he front end or; said lever in fixed relation thereto, a rod aflixed at its lower end. toithe bottom wall of: said casing and; extended upwardly through said leverand out of said casing through the opening in its top, a sleeve mounted on said rodrandg'provided with a flange for engaging, saidcleve'r, a spring encircling saidnrod above said lever and co-operating with saidfiange, and/ nut on the upper end of said rod co-operating with said spring to compress the same and thereby adjust the pressure of the brush upon said commutator, said upturned front wall of said casing co-operating with said lever to limit movement of the latter toward the commutator when the brush has been worn a predetermined amount.

2. In a brush holder for electric motors and the like provided with a commutator, in combination, a casing provided with a bottom wall, a brush-holding lever having its rear end pivoted within said casing and its front end extended out of said casing, a brush secured in fixed relation to the. front end of said lever to engage said commutator, a spring-supporting member afiixed at its lower end to said bot-tom wall and extended upwardly above saidlever, an abutment member on said spring-supporting member, and a spring on said supporting member between said abutment and said lever and acting on the latter to move it toward said bottom wall, and a stop co-opcrating with said lever to limit its movement by said spring.

3. In a brush holder for electric motors and the like provided with a commutator, in combination, a brush-holding lever pivoted at its rear end and provided at its front end with a brush secured in fixed relation thereto to move as one piece therewith, a

supporting member to which said lever is pivoted substantially in a plane tangential to the commutator at the point of contact of the brush therewith, a rod extended above and below said lever and secured at its lower end to said supporting member, an abutment member on said rod above said lever, a spring on said rod between said abutment member and said lever and acting on the latter to move it toward said commutator, and means to limit the movement of said lever by said spring.

4. In a brush holder for electric motors and the like provided with a commutator, in combination, a supporting member, a brush holding lever provided with a brush secured thereto in fixed relation to move as one piece therewith and having its pivot at a substantial distance from the point of contact of the brush with the commutator and substantially in a plane tangential to the commutator at the said point of contact, a rod extended above and below said brushholding lever and fastened at its lower end to said supporting member, a helical spring mounted on said rod above said lever, and means on the said rod for compressing the said spring between it and the brush-holding lever.

In testimony whereof, I have signed my name to this specification.

JOHN LINDALL. 

